#ifndef SG_UNALIGNED_H
#define SG_UNALIGNED_H

/*
 * Copyright (c) 2014-2018 Douglas Gilbert.
 * All rights reserved.
 * Use of this source code is governed by a BSD-style
 * license that can be found in the BSD_LICENSE file.
 */

#include <stdbool.h>
#include <stdint.h> /* for uint8_t and friends */
#include <string.h> /* for memcpy */

#ifdef __cplusplus
extern "C"
{
#endif

        /* These inline functions convert integers (always unsigned) to byte streams
         * and vice versa. They have two goals:
         *   - change the byte ordering of integers between host order and big
         *     endian ("_be") or little endian ("_le")
         *   - copy the big or little endian byte stream so it complies with any
         *     alignment that host integers require
         *
         * Host integer to given endian byte stream is a "_put_" function taking
         * two arguments (integer and pointer to byte stream) returning void.
         * Given endian byte stream to host integer is a "_get_" function that takes
         * one argument and returns an integer of appropriate size (uint32_t for 24
         * bit operations, uint64_t for 48 bit operations).
         *
         * Big endian byte format "on the wire" is the default used by SCSI
         * standards (www.t10.org). Big endian is also the network byte order.
         * Little endian is used by ATA, PCI and NVMe.
         */

        /* The generic form of these routines was borrowed from the Linux kernel,
         * via mhvtl. There is a specialised version of the main functions for
         * little endian or big endian provided that not-quite-standard defines for
         * endianness are available from the compiler and the <byteswap.h> header
         * (a GNU extension) has been detected by ./configure . To force the
         * generic version, use './configure --disable-fast-lebe ' . */

        /* Note: Assumes that the source and destination locations do not overlap.
         * An example of overlapping source and destination:
         *     sg_put_unaligned_le64(j, ((uint8_t *)&j) + 1);
         * Best not to do things like that.
         */

#ifdef HAVE_CONFIG_H
#include "config.h" /* need this to see if HAVE_BYTESWAP_H */
#endif

#undef GOT_UNALIGNED_SPECIALS /* just in case */

#if defined(__BYTE_ORDER__) && defined(HAVE_BYTESWAP_H) && \
    !defined(IGNORE_FAST_LEBE)

#if defined(__LITTLE_ENDIAN__) || (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)

#define GOT_UNALIGNED_SPECIALS 1

#include <byteswap.h> /* for bswap_16(), bswap_32() and bswap_64() */

        // #warning ">>>>>> Doing Little endian special unaligneds"

        static inline uint16_t sg_get_unaligned_be16(const void *p)
        {
                uint16_t u;

                memcpy(&u, p, 2);
                return bswap_16(u);
        }

        static inline uint32_t sg_get_unaligned_be32(const void *p)
        {
                uint32_t u;

                memcpy(&u, p, 4);
                return bswap_32(u);
        }

        static inline uint64_t sg_get_unaligned_be64(const void *p)
        {
                uint64_t u;

                memcpy(&u, p, 8);
                return bswap_64(u);
        }

        static inline void sg_put_unaligned_be16(uint16_t val, void *p)
        {
                uint16_t u = bswap_16(val);

                memcpy(p, &u, 2);
        }

        static inline void sg_put_unaligned_be32(uint32_t val, void *p)
        {
                uint32_t u = bswap_32(val);

                memcpy(p, &u, 4);
        }

        static inline void sg_put_unaligned_be64(uint64_t val, void *p)
        {
                uint64_t u = bswap_64(val);

                memcpy(p, &u, 8);
        }

        static inline uint16_t sg_get_unaligned_le16(const void *p)
        {
                uint16_t u;

                memcpy(&u, p, 2);
                return u;
        }

        static inline uint32_t sg_get_unaligned_le32(const void *p)
        {
                uint32_t u;

                memcpy(&u, p, 4);
                return u;
        }

        static inline uint64_t sg_get_unaligned_le64(const void *p)
        {
                uint64_t u;

                memcpy(&u, p, 8);
                return u;
        }

        static inline void sg_put_unaligned_le16(uint16_t val, void *p)
        {
                memcpy(p, &val, 2);
        }

        static inline void sg_put_unaligned_le32(uint32_t val, void *p)
        {
                memcpy(p, &val, 4);
        }

        static inline void sg_put_unaligned_le64(uint64_t val, void *p)
        {
                memcpy(p, &val, 8);
        }

#elif defined(__BIG_ENDIAN__) || (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)

#define GOT_UNALIGNED_SPECIALS 1

#include <byteswap.h>

        // #warning ">>>>>> Doing BIG endian special unaligneds"

        static inline uint16_t sg_get_unaligned_le16(const void *p)
        {
                uint16_t u;

                memcpy(&u, p, 2);
                return bswap_16(u);
        }

        static inline uint32_t sg_get_unaligned_le32(const void *p)
        {
                uint32_t u;

                memcpy(&u, p, 4);
                return bswap_32(u);
        }

        static inline uint64_t sg_get_unaligned_le64(const void *p)
        {
                uint64_t u;

                memcpy(&u, p, 8);
                return bswap_64(u);
        }

        static inline void sg_put_unaligned_le16(uint16_t val, void *p)
        {
                uint16_t u = bswap_16(val);

                memcpy(p, &u, 2);
        }

        static inline void sg_put_unaligned_le32(uint32_t val, void *p)
        {
                uint32_t u = bswap_32(val);

                memcpy(p, &u, 4);
        }

        static inline void sg_put_unaligned_le64(uint64_t val, void *p)
        {
                uint64_t u = bswap_64(val);

                memcpy(p, &u, 8);
        }

        static inline uint16_t sg_get_unaligned_be16(const void *p)
        {
                uint16_t u;

                memcpy(&u, p, 2);
                return u;
        }

        static inline uint32_t sg_get_unaligned_be32(const void *p)
        {
                uint32_t u;

                memcpy(&u, p, 4);
                return u;
        }

        static inline uint64_t sg_get_unaligned_be64(const void *p)
        {
                uint64_t u;

                memcpy(&u, p, 8);
                return u;
        }

        static inline void sg_put_unaligned_be16(uint16_t val, void *p)
        {
                memcpy(p, &val, 2);
        }

        static inline void sg_put_unaligned_be32(uint32_t val, void *p)
        {
                memcpy(p, &val, 4);
        }

        static inline void sg_put_unaligned_be64(uint64_t val, void *p)
        {
                memcpy(p, &val, 8);
        }

#endif /* __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__  */
#endif /* #if defined __BYTE_ORDER__ && defined <byteswap.h> && \
        *     ! defined IGNORE_FAST_LEBE */

#ifndef GOT_UNALIGNED_SPECIALS

        /* Now we have no tricks left, so use the only way this can be done
         * correctly in C safely: lots of shifts. */

        // #warning ">>>>>> Doing GENERIC unaligneds"

        static inline uint16_t sg_get_unaligned_be16(const void *p)
        {
                return ((const uint8_t *)p)[0] << 8 | ((const uint8_t *)p)[1];
        }

        static inline uint32_t sg_get_unaligned_be32(const void *p)
        {
                return ((const uint8_t *)p)[0] << 24 | ((const uint8_t *)p)[1] << 16 |
                       ((const uint8_t *)p)[2] << 8 | ((const uint8_t *)p)[3];
        }

        static inline uint64_t sg_get_unaligned_be64(const void *p)
        {
                return (uint64_t)sg_get_unaligned_be32(p) << 32 |
                       sg_get_unaligned_be32((const uint8_t *)p + 4);
        }

        static inline void sg_put_unaligned_be16(uint16_t val, void *p)
        {
                ((uint8_t *)p)[0] = (uint8_t)(val >> 8);
                ((uint8_t *)p)[1] = (uint8_t)val;
        }

        static inline void sg_put_unaligned_be32(uint32_t val, void *p)
        {
                sg_put_unaligned_be16(val >> 16, p);
                sg_put_unaligned_be16(val, (uint8_t *)p + 2);
        }

        static inline void sg_put_unaligned_be64(uint64_t val, void *p)
        {
                sg_put_unaligned_be32(val >> 32, p);
                sg_put_unaligned_be32(val, (uint8_t *)p + 4);
        }

        static inline uint16_t sg_get_unaligned_le16(const void *p)
        {
                return ((const uint8_t *)p)[1] << 8 | ((const uint8_t *)p)[0];
        }

        static inline uint32_t sg_get_unaligned_le32(const void *p)
        {
                return ((const uint8_t *)p)[3] << 24 | ((const uint8_t *)p)[2] << 16 |
                       ((const uint8_t *)p)[1] << 8 | ((const uint8_t *)p)[0];
        }

        static inline uint64_t sg_get_unaligned_le64(const void *p)
        {
                return (uint64_t)sg_get_unaligned_le32((const uint8_t *)p + 4) << 32 |
                       sg_get_unaligned_le32(p);
        }

        static inline void sg_put_unaligned_le16(uint16_t val, void *p)
        {
                ((uint8_t *)p)[0] = val & 0xff;
                ((uint8_t *)p)[1] = val >> 8;
        }

        static inline void sg_put_unaligned_le32(uint32_t val, void *p)
        {
                sg_put_unaligned_le16(val >> 16, (uint8_t *)p + 2);
                sg_put_unaligned_le16(val, p);
        }

        static inline void sg_put_unaligned_le64(uint64_t val, void *p)
        {
                sg_put_unaligned_le32(val >> 32, (uint8_t *)p + 4);
                sg_put_unaligned_le32(val, p);
        }

#endif /* #ifndef GOT_UNALIGNED_SPECIALS */

        /* Following are lesser used conversions that don't have specializations
         * for endianness; big endian first. In summary these are the 24, 48 bit and
         * given-length conversions plus the "nz" conditional put conversions. */

        /* Now big endian, get 24+48 then put 24+48 */
        static inline uint32_t sg_get_unaligned_be24(const void *p)
        {
                return ((const uint8_t *)p)[0] << 16 | ((const uint8_t *)p)[1] << 8 |
                       ((const uint8_t *)p)[2];
        }

        /* Assume 48 bit value placed in uint64_t */
        static inline uint64_t sg_get_unaligned_be48(const void *p)
        {
                return (uint64_t)sg_get_unaligned_be16(p) << 32 |
                       sg_get_unaligned_be32((const uint8_t *)p + 2);
        }

        /* Returns 0 if 'num_bytes' is less than or equal to 0 or greater than
         * 8 (i.e. sizeof(uint64_t)). Else returns result in uint64_t which is
         * an 8 byte unsigned integer. */
        static inline uint64_t sg_get_unaligned_be(int num_bytes, const void *p)
        {
                if ((num_bytes <= 0) || (num_bytes > (int)sizeof(uint64_t)))
                        return 0;
                else
                {
                        const uint8_t *xp = (const uint8_t *)p;
                        uint64_t res = *xp;

                        for (++xp; num_bytes > 1; ++xp, --num_bytes)
                                res = (res << 8) | *xp;
                        return res;
                }
        }

        static inline void sg_put_unaligned_be24(uint32_t val, void *p)
        {
                ((uint8_t *)p)[0] = (val >> 16) & 0xff;
                ((uint8_t *)p)[1] = (val >> 8) & 0xff;
                ((uint8_t *)p)[2] = val & 0xff;
        }

        /* Assume 48 bit value placed in uint64_t */
        static inline void sg_put_unaligned_be48(uint64_t val, void *p)
        {
                sg_put_unaligned_be16(val >> 32, p);
                sg_put_unaligned_be32(val, (uint8_t *)p + 2);
        }

        /* Now little endian, get 24+48 then put 24+48 */
        static inline uint32_t sg_get_unaligned_le24(const void *p)
        {
                return (uint32_t)sg_get_unaligned_le16(p) |
                       ((const uint8_t *)p)[2] << 16;
        }

        /* Assume 48 bit value placed in uint64_t */
        static inline uint64_t sg_get_unaligned_le48(const void *p)
        {
                return (uint64_t)sg_get_unaligned_le16((const uint8_t *)p + 4) << 32 |
                       sg_get_unaligned_le32(p);
        }

        static inline void sg_put_unaligned_le24(uint32_t val, void *p)
        {
                ((uint8_t *)p)[2] = (val >> 16) & 0xff;
                ((uint8_t *)p)[1] = (val >> 8) & 0xff;
                ((uint8_t *)p)[0] = val & 0xff;
        }

        /* Assume 48 bit value placed in uint64_t */
        static inline void sg_put_unaligned_le48(uint64_t val, void *p)
        {
                ((uint8_t *)p)[5] = (val >> 40) & 0xff;
                ((uint8_t *)p)[4] = (val >> 32) & 0xff;
                ((uint8_t *)p)[3] = (val >> 24) & 0xff;
                ((uint8_t *)p)[2] = (val >> 16) & 0xff;
                ((uint8_t *)p)[1] = (val >> 8) & 0xff;
                ((uint8_t *)p)[0] = val & 0xff;
        }

        /* Returns 0 if 'num_bytes' is less than or equal to 0 or greater than
         * 8 (i.e. sizeof(uint64_t)). Else returns result in uint64_t which is
         * an 8 byte unsigned integer. */
        static inline uint64_t sg_get_unaligned_le(int num_bytes, const void *p)
        {
                if ((num_bytes <= 0) || (num_bytes > (int)sizeof(uint64_t)))
                        return 0;
                else
                {
                        const uint8_t *xp = (const uint8_t *)p + (num_bytes - 1);
                        uint64_t res = *xp;

                        for (--xp; num_bytes > 1; --xp, --num_bytes)
                                res = (res << 8) | *xp;
                        return res;
                }
        }

        /* Since cdb and parameter blocks are often memset to zero before these
         * unaligned function partially fill them, then check for a val of zero
         * and ignore if it is with these variants. First big endian, then little */
        static inline void sg_nz_put_unaligned_be16(uint16_t val, void *p)
        {
                if (val)
                        sg_put_unaligned_be16(val, p);
        }

        static inline void sg_nz_put_unaligned_be24(uint32_t val, void *p)
        {
                if (val)
                {
                        ((uint8_t *)p)[0] = (val >> 16) & 0xff;
                        ((uint8_t *)p)[1] = (val >> 8) & 0xff;
                        ((uint8_t *)p)[2] = val & 0xff;
                }
        }

        static inline void sg_nz_put_unaligned_be32(uint32_t val, void *p)
        {
                if (val)
                        sg_put_unaligned_be32(val, p);
        }

        static inline void sg_nz_put_unaligned_be64(uint64_t val, void *p)
        {
                if (val)
                        sg_put_unaligned_be64(val, p);
        }

        static inline void sg_nz_put_unaligned_le16(uint16_t val, void *p)
        {
                if (val)
                        sg_put_unaligned_le16(val, p);
        }

        static inline void sg_nz_put_unaligned_le24(uint32_t val, void *p)
        {
                if (val)
                {
                        ((uint8_t *)p)[2] = (val >> 16) & 0xff;
                        ((uint8_t *)p)[1] = (val >> 8) & 0xff;
                        ((uint8_t *)p)[0] = val & 0xff;
                }
        }

        static inline void sg_nz_put_unaligned_le32(uint32_t val, void *p)
        {
                if (val)
                        sg_put_unaligned_le32(val, p);
        }

        static inline void sg_nz_put_unaligned_le64(uint64_t val, void *p)
        {
                if (val)
                        sg_put_unaligned_le64(val, p);
        }

#ifdef __cplusplus
}
#endif

#endif /* SG_UNALIGNED_H */
